1. Field of the Invention
The present invention relates to a method and apparatus for compensating an estimated location of a wireless network element from information collected by heterogeneous terminals, which are capable of estimating a more accurate location of the wireless network element by compensating the information.
2. Description of the Related Art
Recently, a wireless fidelity (WiFi)-based positioning method may provide location information to a user of a wireless communication terminal in an indoor environment and the like, in which a global positioning system (GPS) is unavailable. As an example, the Skyhook Wireless of U.S. constructs a WiFi location database (DB) using a location information collecting method using vehicles. However, considering rapid growth in indoor navigation, indoor location based advertising services, and the like, a technology for constructing a WiFi location DB for providing automated location update and compensation while providing positioning accuracy almost in units of a room size and minimizing cost for collecting.
The WiFi positioning method is being widely used for following reasons.
First, recently, WiFi access points (AP) are spread more and more to reduce a network transmission load caused by large-capacity data transmission. For example, three major mobile communication companies of Korea are competitively constructing the WiFi AP, aiming at supplying two hundred thousand or more of the WiFi APs by the end of 2011 nationwide. Furthermore, those mobile communication companies are planning to supply the WiFi APs to about a thousand of main government and public offices including airports, railway stations, bus terminals, public organizations, and the like, by the first half of 2012.
Second, smart phones that support connection between 3-generation (3G) and WiFi are being spread quite rapidly. Allegedly by Gartner, a market research firm, the supplied number of smart phones is predicted to reach about 57 hundred billions, that is, about 31.5% of the entire number of mobile communication terminals throughout the world, in 2012.
Third, various WiFi-based positioning methods of city levels are being developed. Representatively, a fingerprinting method compares a pre-stored signal pattern with WiFI scan information and determines a location corresponding to a signal pattern most similar to the pre-stored signal pattern as a location of the terminal. The fingerprinting method may increase accuracy of terminal positioning by reducing intervals of collecting the WiFi scan information. Also, according to the fingerprinting method, location information of a WiFi AP is unnecessary. However, considering a pattern characteristic of the fingerprinting method, which is sensitive to variation of indoor environments, WiFi scan information needs to be collected periodically, consequently increasing the cost.
Another example of the WiFi-based positioning methods is a wardriving-based WiFi AP positioning method. This method composites GPS locations of vehicles and WiFi scan information through wardriving, thereby estimating a WiFi AP location. The wardriving method is capable of quickly collecting the WiFi scan information and obtaining more accurate information using a dedicated collecting device. However, as to the estimated AP location, accuracy is not sufficiently high, being about 10 m to 20 m.
Last, a user-involved WiFi AP positioning method is being actively researched in these days. The user-involved WiFi AP positioning method collects an indoor reference location and WiFi scan information through contribution by a check-in service of users of terminals including a heterogeneous WiFi chipset, and estimates a location of a WiFi AP using the indoor reference location and the WiFi scan information. Since the indoor information is collected using a smart phone, accuracy in the estimated AP location is relatively higher in comparison to the wardriving method. Also, real-time recollecting is possible by many and unspecified contribution. However, the user-involved WiFi AP positioning method uses measurement information provided by a heterogeneous smart phone, not by a dedicated device. Accordingly, there is a desire for a method for normalizing and compensating the measurement information.